One thing ive always wondered is if the clattering is a good thing. From what I understand, its the detonation of the diesel, causing a pinging on the cylinder walls. If it sounds soft, then that means that its a less powerful explosion right? Ive run a few gallons of vegetable oil through my car (with a setup under the hood like that when you do a diesel purge) for fun and noticed that at idle the clattering goes away also. With the monark nozzles does your car run better?